APAfter a rocky first round, Brock Lesnar regrouped for the win at UFC 116.

LAS VEGAS — Brock Lesnar rallied from a horrific first-round beating to stop Shane Carwin with a choke in the second round, defending his heavyweight title at UFC 116 on Saturday night.

Lesnar (5-1), the intimidating former pro wrestler and the UFC's biggest pay-per-view star, won his first fight in nearly a year despite taking a pounding in the opening minutes from Carwin, the previously undefeated interim champion.

Lesnar took down Carwin in the second round and got Carwin in an arm triangle choke, forcing Carwin to tap out at the MGM Grand Garden.

"I knew he was getting tired," Lesnar said. "Each shot was less dramatic than the other. ... I stand before you a humble champion, and I'm still the toughest (guy) around."

Lesnar canceled two previous bouts with Carwin (12-1) after developing an intestinal illness that nearly killed him. His first bout since UFC 100 showcased his improving mixed martial arts skills alongside his brute toughness — and he celebrated relatively humbly, with none of the arrogance and bad sportsmanship he showed after beating Frank Mir in his last fight.

In the co-main event in the UFC's hometown, Chris Leben stopped Yoshihiro Akiyama with 40 seconds left in the final round to earn a dramatic victory in Leben's second fight in two weeks. Welterweight Chris Lytle also beat Matt Brown, and veteran Stephan Bonnar stopped Krzysztof Soszynski with a second-round flurry.

The comeback victory is another surprising twist in the unique career path of Lesnar, the former college wrestling champion, professional fake wrestler and Minnesota Vikings tryout player who has become MMA' biggest name, if not its most skilled practitioner, in just six pro fights.

Carwin and Lesnar slammed heavily into the cage in the opening minute, but Carwin quickly got Lesnar on the defensive with an uppercut that staggered him. Carwin punched Lesnar in the head for the better part of two minutes, cutting Lesnar badly over his left eye, yet he survived and even stood up from a barrage that would have stopped most fighters.

The fighters exchanged a high-five before the second round, and Lesnar got on top of Carwin with a takedown move. Lesnar's wrestling skills eventually put him in position to choke Carwin, who might have expended too much energy trying to finish it in the first round.

"My hat is off to him," said Carwin, whose previous 12 fights never reached the second round. "He's the champion. I fell down the mountain, but I'll get back up."

Lesnar dropped out of two scheduled fights with Carwin last fall, citing injuries and fatigue that culminated when he fell seriously ill on a hunting trip in Canada. Lesnar eventually was diagnosed with diverticulitis, an intestinal ailment.

He was pronounced healthy early this year and began training for this long-overdue fight with Carwin, who beat Mir at UFC 111 in New Jersey last March to claim the interim title.

Carwin is a 35-year-old former college wrestler who nurtured a perfect MMA record while working full-time as a mechanical engineer in Colorado. He has none of Lesnar's bluster and mercurial personality, but quietly became a heavyweight champion anyway.

Carwin's greatest strength in his previous fights had been his power, with every opponent dropping in the first round under Carwin's one-punch knockout power. Lesnar somehow survived dozens of shots and thrived.

Just two weeks after beating Aaron Simpson in another Las Vegas show, Leben returned to the octagon as an injury replacement for Wanderlei Silva. Despite one of the quickest turnarounds in recent MMA history, Leben survived Akiyama's skill and landed superior strikes before getting Akiyama in a triangle choke, forcing the touted Japanese judo star to tap out of his second UFC bout.

"It doesn't matter if it's on my feet, on the ground," said Leben, who demanded to fight Silva next. "If I'm in the fight, I get the job done."

Earlier, Bonnar salvaged his career with a dramatic second-round stoppage of Soszynski, who won the fighters' first meeting last February. Bonnar took significant punishment and developed serious cuts in the first round, but he staggered Soszynski with a knee to the face and then landed several dozen left hands to the prone Soszynski's ear before the fight was stopped.

Bonnar (15-7), known as the American Psycho for his slicked-back good looks, ended a three-match losing streak by stopping Soszynski, who beat Bonnar in Australia when the fight was stopped a cut from an inadvertent head butt.

"I like winning ugly, and boy, do I look ugly right now," Bonnar said.